Visually impairing cataract, or clouding of the lens, is the leading cause of preventable blindness in the world. Presently, cataracts are treated by surgical removal of the affected lens and replacement with an artificial intraocular lens (“IOL”). FIG. 1 is a diagram of an eye 100 illustrating anatomical structures related to the surgical removal of a cataract and the implantation of an IOL. The eye 100 comprises an opacified lens 102, an optically clear cornea 104, and an iris 106. A lens capsule (capsular bag 108) located behind the iris 106 of the eye 100 contains the opacified lens 102. More particularly, the opacified lens 102 is seated between an anterior capsule segment (anterior capsule 110) and a posterior capsular segment (posterior capsule 112). The anterior capsule 110 and the posterior capsule 112 meet at an equatorial region 114 of the capsular bag 108. The eye 100 also comprises an anterior chamber 116 located in front of the iris 106 and a posterior chamber 118 located between the iris 106 and the capsular bag 108.
A common technique for cataract surgery is extracapsular cataract extraction (“ECCE”), which involves the creation of an incision near the outer edge of the cornea 104 and an opening in the anterior capsule 110 (i.e., an anterior capsulotomy) through which the opacified lens 102 is removed. The lens 102 can be removed by various known methods. One such method is phacoemulsification, in which ultrasonic energy is applied to the lens to break it into small pieces that are aspirated from the capsular bag 108. Thus, with the exception of the portion of the anterior capsule 110 that is removed in order to gain access to the lens 102, the capsular bag 108 may remain substantially intact throughout an ECCE. The intact posterior capsule 112 provides a support for the IOL and acts as a barrier to the vitreous humor within the posterior chamber 120 of the eye 100.
Following removal of the opacified lens 102, an artificial IOL, which may be designed to mimic the transparency and refractive function of a healthy lens, is typically implanted within the capsular bag 108 through the opening in the anterior capsule 110. The IOL may be acted on and held in a desired position by the zonular forces exerted by a ciliary body 122 and attached zonules 124 surrounding the periphery of the capsular bag 108.
The power of the artificial IOL chosen for a particular patient may be selected by a surgeon based on the measured optical characteristics of the patient's eye and the desired location of the IOL along the patient's optical axis following implantation. Despite the surgeon's best efforts, however, corneal healing after cataract surgery may change the refractive properties of the eye. Additionally, the healing process may result in IOL displacement within the capsular bag 108. Corneal healing and lens displacement may cause refractive errors after cataract surgery, prohibiting a desired refraction target from being achieved. Conventional techniques for correcting post cataract surgery refractive errors (e.g., LASIK-type procedures) may be insufficient as such procedures are similarly impacted by post-surgical corneal shape change.